Present day automobile headlights are in the form of sealed beam units. In most cases, the headlamp envelope has a generally round or rectangular front wall and a curved rear wall. Bayonnet-type electrical connectors project from the rear wall of the envelope by which the unit is connected electrically to the automobile's electrical system. Also projecting from that rear wall in the midst of the terminals is a hollow, thin-walled sealed glass stem by which a vacuum was drawn in the sealed beam unit at the time of its manufacture. That stem is the most fragile part of the unit and must be protected.
One collapsible carton used extensively heretofore to contain a headlamp such as this has four hinged-together walls which square up to form a generally rectangular tube. Cover flaps are hinged to the upper and lower edges of the walls which suffice to close off the upper and lower ends of the carton.
Also, in order to secure the headlamp within the carton so that it cannot move around, a flexible strap is provided inside the carton having its opposite ends secured to opposite walls of the carton. This strap folds out automatically when the carton is erected. When a headlamp is inserted into the carton between the strap and the opposite carton wall, the strap flexes to conform to the curved rear wall of the lamp and, in doing so, presses the front face of the unit flush against the adjacent carton wall so that the lamp is captured securely between the strap and that wall. Usually also, a notch is provided in the strap midway along its length to accommodate the terminals and glass stem projecting from the rear wall of the headlamp.
One problem which has plagued the prior cartons of this general type stems from the fact that when the headlamp unit is inserted into the carton either by man or machine, sometimes the unit is pushed too far into the carton with the result that the lamp securing strap tears at some location along its length where the stress is greatest. Resultantly, the headlamp is no longer secured firmly within the carton and is free to move about therein.
In this connection, it should be borne in mind that the front face of the headlamp may be rectantular in which case its edges are positioned right at the edges of the opposing carton wall. Furthermore, it is customary to stack a number of headlamp-containing cartons in larger boxes or crates for shipment. This means that, if the cartons are all oriented the same way in the crate, the edges of the rectangular lamps in adjacent cartons lie right next to one another. Consequently, if a lamp is free to move within its carton, it can be driven against a corner of the carton with sufficient force to impact an edge of a bulb in an adjacent carton with the result that one or both bulbs may crack. Since, in order to operate properly, the headlamp must be under a vacuum, the slightest leak in the glass envelope ruins the headlamp.
Prior cartons of this general type are disadvantaged also in that, when the carton is squared up, the headlamp-retaining strap does not always open out into its correct position. This is particularly so with the larger cartons. In other words, when the carton is in its knocked-down condition, which is its condition after the folding and glueing operations and when a number of such cartons are shipped, the lamp-retaining strap is sandwiched between the carton walls. In some cases, when the carton is erected from that flattened condition, the strap unfolds the wrong way so that it does not occupy its proper position within the carton, but rather lies too close to the carton walls. Resultantly, the strap is in no condition to retain a headlamp inserted into the carton.